Oranges, like most fruits and vegetables have specific growing seasons. They grow only under certain climatic conditions such as occur in regions of Florida, Arizona, California, Texas, Brazil, Spain, Italy, Israel and Egypt and are available only for limited periods of time during the year. Thus, certain oranges may periodically be in short supply. For instance, Florida Valencia oranges which are used in most commercial orange juice products are available only from April through August. In order to have good quality orange juice available year-round, the orange juice must be processed for storage and distribution.
In the following discussion, references are made to aroma and flavor compounds present in orange juice and orange juice concentrates. It is known that organoleptic attributes of any commercial beverage are important to consumer acceptance; however, such attributes are uniquely involved in orange juice acceptability. The term organoleptic is defined as "affecting or employing one or more of the organs of special sense", i.e. taste, smell, etc.
The challenge of producing an orange juice product which is acceptable to a broad range of consumers, involves making a unique product having acceptable flavor, i.e. taste; distinctive aroma, i.e. smell; acceptable appearance, i.e. sight; and satisfactory mouthfeel, i.e. touch. The aroma and flavor compounds in oranges affect each of these organoleptic properties. This is surprising because although there are many aroma and flavor compounds which comprise orange juice, they are present in relatively small amounts.
The difficulty of producing a unique orange juice concentrate having superior quality can be appreciated when one considers that orange juice concentrates have been available for several decades and that natural orange juice products are enjoyed by a large proportion of the general public. Thus in order to find broad acceptance a new orange juice concentrate product must overcome the acquired taste preferences of a large segment of the orange juice-consuming public.
Nevertheless, an important objective achieved by the present invention is that a natural orange juice concentrate product is prepared, and a process for its production is provided, which are uniquely different from previously known orange juice products and processes. It is surprising that the orange juice concentrate of this invention when reconstituted is superior to, and distinguishable from, freshly squeezed orange juice. This distinction is in taste as well as product stability. These and other benefits are achieved because the product and processes described herein offer unexpected improvements in virtually all of the organoleptic senses mentioned above. These unexpected improvements and advantages are described and illustrated hereinafter.
Since orange juice contains about 80% to 90% water, the most economical way to store and distribute the juice is in a concentrated form. The bulk of the orange juice commercially processed in the United States since 1950 has been as a frozen concentrated orange juice product.
Most commercial concentration processes utilize evaporation techniques to remove the bulk of the water from the juice. However, it is widely recognized that evaporation techniques result in the undesired removal or loss of volatile aroma and flavor compounds along with water, thereby resulting in a significant deterioration in quality and overall aroma and flavor of the concentrated juice.
Evaporation processes involve heating the juice under conditions which promote oxidation of compounds in the juice. This can cause the aroma and flavor compounds in the orange juice to be chemically altered. For instance, lipids can be oxidized and the amino acids and sugars can undergo browning reaction. Such degradation products can cause off-flavors in the orange juice concentrates.
Numerous methods have been devised to compensate for the loss of aroma and flavor during evaporation concentration processes. For instance, U.S. Pat. No. 3,140,187, issued to Brent (1964) discloses a method of minimizing the overall loss of aroma and flavor compounds by collecting "essence" of the juice. Essence is the term applied to the first 15% to 20% of the water which is removed through evaporation and which contains a significant amount of volatile aroma and flavor compounds. The escaping essence is condensed, the aroma and flavor compounds recovered and then added back to concentrated juice. However, this procedure is not totally satisfactory because only a fraction of the escaping aroma and flavor volatile compounds can be collected and recovered. Thus, there is necessarily a net loss in overall aroma and flavor of the final concentrated product.
Others have tried different procedures for adding back certain volatile compounds and essences to concentrated orange juice to enhance the overall flavor and consumer acceptability of the juice. Ahmed et al., J. Agri, Food Chemistry, 1978, 368-372, describe the addition of certain volatile compounds of essences to juice concentrate after it is recovered from the evaporator. The objective was to match the aroma and flavor found in fresh orange juice.
It is fairly widely recognized that while evaporation concentration processes are useful and fairly effective, there is still a significant loss of aroma and flavor compounds which occurs.
Freeze concentration equipment provides an alternative to the use of evaporators. In freeze concentrators the objective is to remove water in the form of ice crystals.
U.S. Pat. No. 2,187,572, issued to Meinzer (1940) describes an orange juice concentrate which was prepared by extracting juice, centrifuging the juice to recover a pulp portion and provide a liquid centrifugate, freeze concentrating the centrifugate, and adding back the pulp portion to the concentrated juice. Meinzer suggests that the resulting juice product when reconstituted with water approaches the taste of the starting juice. Specific concentrations of volatile aroma and flavor compounds, and the identification of the key compounds retained within his pocket are not described.
Schreier et al., Chem. Microbiol. Technol. Lebensm, 6, 78-83 (1979) analyzed the behavior of volatile aroma compounds during freeze concentration of orange juice. During the course of freeze concentration the aroma and flavor compounds were analyzed by gas chromatography and quantitatively determined in the successive juice concentrates as well as in the successively separated ice. Significant amounts of aroma and flavor compounds were found to be removed in separated ice. Average loss of aroma and flavor compounds in the ice during each successive concentration was estimated to be around 12%. It is evident also that a loss of overall quality occurred because a number of oxidation products were formed during this freeze concentration process, such as nootkatone, carvone, geraniol, and alpha-terpineol. The formation of these oxidation products and similar compounds can result in a juice product having a notable off-flavor.
Although Schreier employed a freeze concentration process, his analytical data reveal that significant losses of volatile compounds were experienced. Moreover, because of the open processing used by both Meinzer and Schreier et al., oxidation products are produced. Ideally, in freeze concentration only pure ice should be removed without removing any of the aroma and flavor compounds present in the original juice. If the recovered ice contains occluded aroma and flavor compounds, an inferior quality juice concentrate is produced.
From the foregoing discussion, it can be seen that a generalized procedure for producing an orange juice concentrate involves first extracting the juice from the orange and separating the juice from the rag and seed material. The juice can be separated into a pulp portion and a serum portion. The pulp may be further treated to separate the useful pulp from any small seeds and, if desired, to alter the quantity and size of the pulp. Eventually the pulp is recombined with processed serum.
The serum is concentrated by removing water to produce a concentrated serum. Some serum concentration processes are done in the presence of pulp. Typically, a last step may involve blending the concentrate with a desired amount of pulp to produce a final concentrated product which can be packaged and distributed.
The serum, which remains after pulp, rag, and seed are separated, is known to contain essentially water and the compounds which are responsible for the distinct orange aroma and flavor. As a matter of fact, however, it is probably not possible to categorically assign one specific function to any given ingredient. For instance, a chemical compound which contributes to the orange aroma may also contribute to the orange flavor.
A process for making an orange juice concentrate which can be a pasteurized product and which has substantially 100% of the non-volatile compounds originally present in the serum and at least 65% of the aroma and flavor volatile compounds is very desirable. Moreover, if such a process did not cause oxidative degradation of the solids in the juice, this process would produce a concentrate which, when diluted, would taste as good as, or better, than the original juice.
It is an object of the present invention to produce a natural orange juice concentrate having at least 35% solids. The solids comprise pulp, non-volatile compounds and at least 65% of the aroma and flavor volatile compounds which were present in the orange juice. It is believed that such a concentrated orange juice product has never been made before this invention. These retained volatile and non-volatile compounds are the very compounds which contribute importantly to the pleasant flavor and aroma of the product.
An important contributor to the fruity character of orange juice aroma and flavor is ethyl butyrate. At least about 0.1% of the aroma and flavor volatile compounds present in the orange juice concentrate of the instant invention is ethyl butyrate. A second important volatile compound, limonene, is also retained.
It is a further object of this invention to produce an orange juice concentrate which when reconstituted tastes as good as, or better, than the starting juice.
It is still another object of this invention to produce an orange juice concentrate which can be used as a flavorant in beverages, including carbonated beverages, dry mixes and alcoholic beverages, candies, baked goods and culinary mixes.
A preferred object of this invention is to produce an orange juice concentrate which contains less than organoleptically detectable amounts of hydrogen sulfide and which is substantially free of microorganisms, enzyme activity and oxidative degradation products.
These and other objects of this invention will become apparent by the description of the invention below.
All percentages herein are by weight unless otherwise defined.